In the early 90's the band Spirit played at Music Revolution, the Tampa record store i was a part-owner of...and Jay Ferguson played my Guild D-25. Got all their signatures (not on the guitar); RIP Randy California!
Los Lobos, Indigo Girls , Bruce Cockburn (gifted him a pack of Zig-Zags), backstage Indigo Girls signed pass.
I've never really pursued that kind of memorabilia.
Oh yeah, Marky Mark (nursing a major Miami hangover) signed autographs for his fans and his bodyguards made us keep people out of the store the whole time he was signing, so dreams of big sales went up in smoke on that one...and he charged a grand for the privilege!